Refactor code indexer (#9313)

* Refactor code indexer

* fix test

* fix test

* refactor code indexer

* fix import

* improve code

* fix typo

* fix test and make code clean

* fix lint

modules/indexer/code/git.go

@@ -0,0 +1,147 @@
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package code
+
+import (
+	"strconv"
+	"strings"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+)
+
+type fileUpdate struct {
+	Filename string
+	BlobSha  string
+}
+
+// repoChanges changes (file additions/updates/removals) to a repo
+type repoChanges struct {
+	Updates          []fileUpdate
+	RemovedFilenames []string
+}
+
+func getDefaultBranchSha(repo *models.Repository) (string, error) {
+	stdout, err := git.NewCommand("show-ref", "-s", git.BranchPrefix+repo.DefaultBranch).RunInDir(repo.RepoPath())
+	if err != nil {
+		return "", err
+	}
+	return strings.TrimSpace(stdout), nil
+}
+
+// getRepoChanges returns changes to repo since last indexer update
+func getRepoChanges(repo *models.Repository, revision string) (*repoChanges, error) {
+	if err := repo.GetIndexerStatus(); err != nil {
+		return nil, err
+	}
+
+	if len(repo.IndexerStatus.CommitSha) == 0 {
+		return genesisChanges(repo, revision)
+	}
+	return nonGenesisChanges(repo, revision)
+}
+
+func isIndexable(entry *git.TreeEntry) bool {
+	if !entry.IsRegular() && !entry.IsExecutable() {
+		return false
+	}
+	name := strings.ToLower(entry.Name())
+	for _, g := range setting.Indexer.ExcludePatterns {
+		if g.Match(name) {
+			return false
+		}
+	}
+	for _, g := range setting.Indexer.IncludePatterns {
+		if g.Match(name) {
+			return true
+		}
+	}
+	return len(setting.Indexer.IncludePatterns) == 0
+}
+
+// parseGitLsTreeOutput parses the output of a `git ls-tree -r --full-name` command
+func parseGitLsTreeOutput(stdout []byte) ([]fileUpdate, error) {
+	entries, err := git.ParseTreeEntries(stdout)
+	if err != nil {
+		return nil, err
+	}
+	var idxCount = 0
+	updates := make([]fileUpdate, len(entries))
+	for _, entry := range entries {
+		if isIndexable(entry) {
+			updates[idxCount] = fileUpdate{
+				Filename: entry.Name(),
+				BlobSha:  entry.ID.String(),
+			}
+			idxCount++
+		}
+	}
+	return updates[:idxCount], nil
+}
+
+// genesisChanges get changes to add repo to the indexer for the first time
+func genesisChanges(repo *models.Repository, revision string) (*repoChanges, error) {
+	var changes repoChanges
+	stdout, err := git.NewCommand("ls-tree", "--full-tree", "-r", revision).
+		RunInDirBytes(repo.RepoPath())
+	if err != nil {
+		return nil, err
+	}
+	changes.Updates, err = parseGitLsTreeOutput(stdout)
+	return &changes, err
+}
+
+// nonGenesisChanges get changes since the previous indexer update
+func nonGenesisChanges(repo *models.Repository, revision string) (*repoChanges, error) {
+	diffCmd := git.NewCommand("diff", "--name-status",
+		repo.IndexerStatus.CommitSha, revision)
+	stdout, err := diffCmd.RunInDir(repo.RepoPath())
+	if err != nil {
+		// previous commit sha may have been removed by a force push, so
+		// try rebuilding from scratch
+		log.Warn("git diff: %v", err)
+		if err = indexer.Delete(repo.ID); err != nil {
+			return nil, err
+		}
+		return genesisChanges(repo, revision)
+	}
+	var changes repoChanges
+	updatedFilenames := make([]string, 0, 10)
+	for _, line := range strings.Split(stdout, "\n") {
+		line = strings.TrimSpace(line)
+		if len(line) == 0 {
+			continue
+		}
+		filename := strings.TrimSpace(line[1:])
+		if len(filename) == 0 {
+			continue
+		} else if filename[0] == '"' {
+			filename, err = strconv.Unquote(filename)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		switch status := line[0]; status {
+		case 'M', 'A':
+			updatedFilenames = append(updatedFilenames, filename)
+		case 'D':
+			changes.RemovedFilenames = append(changes.RemovedFilenames, filename)
+		default:
+			log.Warn("Unrecognized status: %c (line=%s)", status, line)
+		}
+	}
+
+	cmd := git.NewCommand("ls-tree", "--full-tree", revision, "--")
+	cmd.AddArguments(updatedFilenames...)
+	lsTreeStdout, err := cmd.RunInDirBytes(repo.RepoPath())
+	if err != nil {
+		return nil, err
+	}
+	changes.Updates, err = parseGitLsTreeOutput(lsTreeStdout)
+	return &changes, err
+}